Vodafone calling me

HELP! Vodafone has been calling me from ‭09 977 1141‬ multiple times (at least 6) over the last 2 weeks. Each time they have called it has not been at a convenient time. Earlier today I was woken from a sound sleep, answered the phone and then the call was dropped!

No message has been left. The number being called from does not take inbound calls. As we have had some service issues, I would like to know why Vodafone is calling and discuss these.

What number can I call at what times of day to talk to whoever it is who is trying to call me?